PA-34 Electrical Short Melted Rudder Cable
Piper PA-34-220T Seneca V G-OXFF of Oxford Aviation Academy was about to enter the runway for takeoff at Oxford Airport on 2 November 2018 when the instructor noticed the rudder pedals felt soft and was “too easy to move”. The student confirmed they did not feel right, so they abandoned the planned flight and returned to the hangar for investigation.
Safety Investigation
The UK Air Accident Investigation Branch (AAIB) investigation report highlights the need for attention on EWIS (Electrical Wiring Interconnection Systems) of all sizes of aircraft:
This Piper Seneca V was fitted with a Garmin 1000 fully integrated cockpit and avionic suite. The system is reliant on electrical power and has a standby battery to keep the system running in the unlikely event of a twin-generator and main battery failure.
Inspection of the aircraft revealed the right rudder cable had chafed against the standby battery wiring and shorted to earth.
OAA PA-34 G-OXFF Chafed Wiring (Credit: AAIB)
The heat generated by the electrical short had melted through the steel-braided rudder cable.
OAA PA-34 G-OXFF Severed Rudder Control Cable (Credit: AAIB)
Safety Action
This potentially serious risk to airworthiness was brought to the attention of the manufacturer, the CAA, EASA and the FAA. The CAA took immediate steps to inform owners and operators of similarly configured Piper Seneca V aircraft.
The manufacturer has subsequently issued a mandatory Service Bulletin (No 1337) which gives instructions to reroute a portion of the emergency power wiring to improve the clearance from the rudder control cables.
OAA PA-34 Senecas at Oxford (Credit: Tl9380 at the English Wikipedia, GNU Free Documentation License)
Safety Resources
- S-92A Flying Control Restriction on Wiring Loom
- C-130 Fireball Due to Modification Error
- UPDATE 1 June 2019: ERJ-190 Flying Control Rigging Error
- UPDATE 18 November 2020: Embraer ERJ-190 EWIS Production Quality a Factor in Fire
- UPDATE 27 December 2020: Fire-Fighting AS350 Hydraulics Accident: Dormant Miswiring
- UPDATE 8 February 2021: RCAF Investigate Defect on Newly Delivered CH-148 Cyclone (S-92)
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